It is known in the art relating to internal combustion engines to provide for deactivation of up to half of the engine cylinders in order to improve fuel economy where possible by operating fewer cylinders in a more efficient load range. In some engine arrangements, cylinder deactivation is provided by so-called switching lifters, which are hydraulically actuated to switch from normal actuation of the intake and exhaust valves to a telescoping mode in which the engine valves are deactivated. Simultaneously, fuel injection to the deactivated cylinders is cut off, allowing the pistons to continue reciprocating with a minimum of friction loss while the remaining cylinders drive the engine in a more efficient power mode.
To control hydraulic deactivation of the lifters, as well as shutting off of the injectors, a deactivation control system is provided. This system provides both hydraulic control passages and electrical control apparatus, including solenoid-actuated hydraulic valves, which are electrically operated to control operation of the hydraulic system for actuating the switching lifters. Such features may be packaged in any suitable manner, and may be contained in a lifter oil manifold assembly (LOMA) containing electrical connection terminals, wires and solenoids for operating the solenoid valves.
Individual test procedures have been developed for testing a cylinder deactivation control, or LOMA, prior to installation in an engine and for testing operation of the system after installation in an engine to diagnose operational problems that may be encountered. However, a need has existed for an easy to use multifunction test device that can be applied during engine build, in dynamometer testing, during vehicle development and for vehicle service diagnosis in the field. Such a device will preferably comprise a deactivation multi tester that can be used to perform comprehensive system testing, reveal possible root causes of failures, be simple to use and require no elaborate instrumentation.